CN110887565A - Push-broom type airborne hyperspectral imaging system with ultra-large field of view and imaging method thereof - Google Patents
Push-broom type airborne hyperspectral imaging system with ultra-large field of view and imaging method thereof Download PDFInfo
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Abstract
The invention discloses a push-broom type airborne hyperspectral imaging system with an oversized view field and an imaging method thereof. The system adopts a cascade optical imaging structure and consists of a primary concentric spherical lens, a secondary relay image rotating micro lens group and a tertiary concentric light splitting imaging lens group, wherein the primary system and the tertiary system are respectively positioned at two sides of an aperture diaphragm; the primary concentric spherical lens adopts a four-piece type concentric asymmetric structure, the secondary relay image rotation micro-lens group adopts an improved Petzval structure, and the tertiary concentric light splitting imaging lens group adopts a concentric total reflection structure; the primary system and the secondary system can independently eliminate most of self geometric aberration and can further balance residual aberration through integral joint optimization; the three-stage system is integrated on one optical glass substrate, so that the stability of the system is improved, and the system is suitable for batch production. The spectral imaging system provided by the invention overcomes the problem that the lengths of the field of view and the slit are mutually restricted, realizes the ultra-large field of view spectral imaging, and has strong light collecting capacity, high stability and excellent imaging performance.
Description
Technical Field
The invention relates to an optical system for fine spectral analysis and an imaging method thereof, in particular to a push-broom type airborne hyperspectral imaging system which adopts a cascade type optical imaging structure, is easy to process, has a large field of view and an imaging method thereof.
Background
The concept of imaging spectroscopy was first proposed by the Jet Propulsion Laboratory (JPL) in the united states. The method is a revolutionary leap in the development process of remote sensor technology, and brings the current spectral remote sensing technology to the forefront. The hyperspectral imaging refers to an imaging spectrum technology with spectral resolution reaching the nanometer order of magnitude, is a novel remote sensing technology starting in the early 80 s of the 20 th century, can simultaneously acquire spectral information and two-dimensional spatial information of a target object, has the advantage of map unification, can qualitatively and quantitatively detect the geometric structure and the physicochemical characteristics of the target object, has special identification capability, is a revolutionary leap in the development history of the remote sensing technology, becomes a main technical means of current-generation space-to-ground observation and a research hotspot in the field of remote sensing, and particularly in military application, the technology can be used for identifying camouflage, detecting martial arts, detecting submarines, detecting underwater dangerous objects and the like; and the method can also be used for analysis, classification, forecast evaluation and the like of environment, ecology, crops, pest control, geology, resources, atmosphere and the like.
In order to meet the continuously improved application requirements in the fields of future quantitative national soil resource investigation, battlefield environment real-time monitoring, accurate agricultural evaluation and the like, more accurate and rapid remote sensing detection is realized, spectral image data with high reliability and high timeliness is obtained, and a hyperspectral imaging system is required to have high spatial resolution and spectral resolution and also have high time resolution. The spatial resolution, the time resolution and the spectral resolution are important performance indexes for measuring a hyperspectral imaging system, the spatial resolution and the time resolution respectively decrease and increase along with the increase of a field of view of an optical system, and the problem that the spatial resolution and the time resolution are mutually restricted is solved. Therefore, the development of a hyperspectral imaging system with excellent imaging performance, high stability, high spectral resolution, easy implementation, low cost and large field of view is very urgent and has wide application prospect.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the hyperspectral imaging system and the imaging method thereof, wherein the hyperspectral imaging system has the advantages of compact structure, excellent imaging performance, high stability, high spectral resolution, low cost and large field of view.
In order to achieve the purpose, the technical scheme adopted by the invention is to provide a push-broom type airborne hyperspectral imaging system with an ultra-large view field, which is a cascading optical imaging structure and sequentially comprises a primary concentric spherical lens system, a secondary relay image-rotating micro lens group, a three-level concentric spectroscopic imaging lens group and a detector focal plane along the incident direction of light rays, wherein the primary concentric spherical lens system and the three-level concentric spectroscopic imaging lens group are respectively positioned at two sides of an aperture diaphragm, and the hyperspectral imaging system meets telecentric imaging at the image side;
the primary concentric spherical lens system is of a concentric asymmetric structure and has a focal lengthf 1 Is less than or equal to 80mmf 1 Less than or equal to 110 mm; the optical elements are a first negative meniscus spherical lens (11), a first positive plano-convex spherical lens (12), a second positive plano-convex spherical lens (13) and a second negative meniscus spherical lens (14) in sequence, and the normalized value of the focal length of each lens relative to the focal length of the system corresponds tof’ 11、f’ 12、f’ 13、f’ 14Satisfies the condition of-2.88 ≤f’ 11≤-2.52、1.02≤f’ 12≤1.13、1.02≤f’ 13≤1.13、-2.88≤f’ 14Less than or equal to-2.52; the refractive index of each lens material is sequentially corresponding ton 11、n 12、n 13、n 14Satisfies the condition of 1.65 ≤n 11≤1.90、1.45≤n 12≤2.0、1.45≤n 13≤2.0、1.65≤n 14≤1.90；
The secondary relay image transfer micro lens group comprises a plurality of sub imaging systems and the focal length of a single sub imaging systemf 2 Is less than or equal to 25mmf 2 Less than or equal to 30 mm; the optical elements are a first biconvex lens (21), a first biconvex lens group (22), a second biconvex lens group (23) and a first meniscus thick lens (24) in sequence, the first biconvex lens group (22) consists of a second biconvex lens (221) and a second meniscus thick lens (222), and the second biconvex lens group (23) consists of a meniscus negative lens (231) and a third biconvex lens (232); the normalized value of each lens focal length relative to the system focal length is sequentially corresponding tof’ 21、f’ 221、f’ 222、f’ 231、f’ 232 、f’ 24， Satisfies the condition of 0.52 ≤f’ 21≤0.55、0.13≤f’ 221≤0.17、-4.92≤f’ 222≤-4.58、0.88≤f’ 231≤0.93、0.26≤f’ 232≤0.29、-0.16≤f’ 24Less than or equal to-0.14; the refractive index of each lens material is sequentially corresponding ton 21、n 221、n 222、n 231、n 232、n 24Satisfies the condition of 1.50 ≤n 21≤1.80、1.40≤n 221≤1.85、1.45≤n 222≤2.0、1.45≤n 231≤2.0、1.40≤n 232≤1.85、1.45≤n 24≤2.0；
The three-stage concentric light splitting imaging lens group comprises a plurality of sub light splitting imaging systems with concentric total reflection structures, optical elements of the three-stage concentric light splitting imaging lens group are a main mirror, a grating and three mirrors in sequence, the main mirror and the three mirrors are spherical reflectors, the grating is a spherical holographic grating, and the focal length of a single sub light splitting imaging systemf 3 Is less than or equal to 100mmf 3 Less than or equal to 130mm, the normalized radius of curvature of the focal length of the imaging system is sequentially corresponding toR 32、R 33 、R 34Satisfies the condition of-0.56 ≤R 32≤-0.50、-0.29≤R 33≤-0.26、-0.56≤R 34Less than or equal to-0.50, and the density of the grating grooves is 400-450 line pairs per millimeter.
One kind of super largeViewing field push-broom type airborne hyperspectral imaging system and total focal length thereoffIs less than or equal to 40mmfLess than or equal to 60 mm. The omega of the full view field is more than or equal to 0 degree and less than or equal to 140 degrees. The length L of the optical cylinder is 240 mm-250 mm. Its spectral resolution is 2 nm/pixel.
The sub-spectroscopic imaging system of the three-level spectroscopic imaging group is integrated on a meniscus optical glass substrate with the refractive index of n, and the value range of n is more than or equal to 1nLess than or equal to 2.5, the grating is positioned on the front concave surface of the glass substrate, and the main mirror and the three mirrors are positioned on the back spherical surface of the glass substrate.
The technical scheme of the invention also comprises an imaging method of the push-broom type airborne hyperspectral imaging system with the ultra-large view field, which comprises the following steps:
(1) a large-range target object passes through a primary concentric spherical lens system to obtain a primary image with a large view field on a first curved image surface;
(2) the large-view-field primary image obtained on the curved surface is taken as a target object of the secondary relay image transfer micro-lens group, and after the secondary relay image transfer micro-lens group performs field-of-view relay imaging, a corresponding independent field-of-view plane image is obtained on the second curved surface;
(3) the obtained independent view-dividing plane image is used as a target object of a three-level concentric spectral imaging system, and spectral images with different wavelengths of each independent view-dividing field are obtained on a detector after corresponding spectral imaging component light and relay imaging;
(4) and carrying out splicing and fusion processing on the spectral images of the sub-fields to obtain the spectral image of the ultra-large field.
The push-broom type airborne hyperspectral imaging system with the ultra-large view field provided by the invention adopts the cascade type optical imaging structure, and effectively combines the advantages of the optical system with the concentric structure and the optical system with the Petzval structure, so that high-quality and high-resolution spectral images in the ultra-large view field range are realized. The invention principle is as follows: the primary system adopts a large-field concentric asymmetric ball lens to obtain a large-field intermediate image with uniform aberration on a curved surface, and the system is simpler and more convenient to perform pupil matching with the secondary system and the tertiary system due to asymmetry; the secondary system is a plurality of groups of same relay image transfer micro lenses, each group adopts a biconvex lens, two groups of double-cemented lenses and a meniscus negative lens close to an image surface, residual aberration correction and field division imaging can be well performed on the intermediate image acquired by the primary system, further achromatization is performed by matching and optimizing selection of double-cemented lens group optical glass materials, and a multi-component field image with the highest diffraction limit is provided for the three-stage light splitting system; the three-stage concentric light splitting imaging system is a plurality of groups of same inverse/diffraction mixed optical systems based on spherical grating light splitting, each group consists of a main mirror, a grating and three mirrors, the three mirrors are integrated on an optical glass substrate, the curvature radiuses of the main mirror and the three mirrors are the same, the main mirror and the three mirrors are integrated on a reflecting mirror and are positioned on the rear surface of the glass substrate, and the grating is positioned on the front spherical surface of the glass substrate. The multi-component field image acquired by the secondary system is taken as a target object, and diffraction spectroscopy and relay imaging are carried out to obtain a corresponding spectral image. The novel high spectral system with the cascade imaging structure solves the problem that the field of view and the slit length of the traditional push-broom imaging system are restricted mutually, realizes large field of view and high spectral resolution, and has wide application prospect.
Compared with the prior art, the invention has the beneficial effects that:
1. the optical system provided by the invention has a field of view of not less than 0 degree and not more than omega and not more than 140 degrees, a wide detectable range and high detection and identification efficiency; the imaging performance is close to the diffraction limit in the full visual field range.
2. The optical system provided by the invention has high spectral resolution which reaches 2 nm/pixel.
3. The structure of the optical system provided by the invention is more beneficial to the matching of pupils when systems at all levels are connected.
4. The primary imaging system and the tertiary imaging system in the optical system provided by the invention both adopt concentric structures, and have the advantages of easy installation and adjustment and good stability.
5. The optical system provided by the invention meets the telecentric light path at the image space, and the surface illumination of the receiving device is uniform.
Drawings
FIG. 1 is a schematic diagram illustrating an operating principle of a push-broom type airborne hyperspectral imaging system with a very large field of view according to an embodiment of the present invention;
FIG. 2 is a schematic view of an optical structure of a push-broom type airborne hyperspectral imaging system with a very large field of view provided by an embodiment of the invention;
fig. 3 to fig. 5 are schematic optical structure diagrams of imaging systems of each stage in the push-broom type airborne hyperspectral imaging system with an oversized view field according to the embodiment of the invention;
FIG. 6 is a schematic view of an optical path of a push-broom type airborne hyperspectral imaging system with a very large field of view according to an embodiment of the invention;
FIG. 7 is a row diagram of ray tracing points of the push-broom type airborne hyperspectral imaging system with a very large field of view provided by the embodiment of the invention;
FIG. 8 is a graph of energy concentration for a push-broom type airborne hyperspectral imaging system with a very large field of view according to an embodiment of the invention;
FIG. 9 is a graph of relative irradiance of a push-broom airborne hyperspectral imaging system with a very large field of view on the surface of a receiver device according to an embodiment of the invention;
FIG. 10 is a graph of an optical transfer function of the push-broom type airborne hyperspectral imaging system with an oversized field of view provided by the embodiment of the invention.
In the figure, 1, a primary concentric sphere lens; 11. a meniscus spherical negative lens of the primary concentric spherical lens; 12. a plano-convex spherical positive lens of the primary concentric spherical lens; 13. a plano-convex spherical positive lens of the primary concentric spherical lens; 14. a meniscus spherical negative lens of the primary concentric spherical lens; 15. an image plane of the primary concentric spherical lens; 2. a secondary relay micro-lens group; 21. a spherical positive lens of the secondary relay image transfer micro lens; 22. a spherical positive lens of the secondary relay image transfer micro lens; 23. a spherical negative lens of the secondary relay image transfer micro lens; 24. a spherical negative lens of the secondary relay image transfer micro lens; 25. a spherical positive lens of the secondary relay image transfer micro lens; 26. a spherical negative lens of the secondary relay image transfer micro lens; 27. an image surface of the secondary relay image transfer micro-lens system (an incident slit of the three-level concentric light splitting imaging lens); 3. a three-stage concentric spectroscopic imaging lens group; 31. a three-stage concentric spectral imaging lens glass substrate; 32. a lens primary mirror for three-stage concentric spectroscopic imaging; 33. grating of the three-level concentric light splitting imaging lens; 34. three mirrors of the three-level concentric light splitting imaging lens; 35. a receiver plane (image plane) of the three-stage concentric spectroscopic imaging lens; 4. and a detector.
Detailed Description
The technical scheme of the invention is further explained by combining the drawings and the embodiment.
Example 1:
in the optical system provided by the embodiment, the F number is F2.6, the working wavelength is in a visible light range, the total focal length of the system is 50.9mm, the full field angle is 120 °, the system cylinder length is 242mm, the spectral resolution is 2nm/pixel, and the refractive index of the glass substrate is 1.65.
Referring to the attached drawing 1, which is a schematic diagram of the working principle of the optical system provided in this embodiment, the push-broom type airborne hyperspectral imaging system with an ultra-large field of view is composed of a primary concentric sphere lens 1, a secondary relay image-rotating microlens set 2, a three-level concentric spectroscopic imaging lens set 3, and a detector 4.
Referring to fig. 2, it is a schematic diagram of a single channel structure of the push-broom type airborne hyperspectral imaging system with an ultra-large field of view provided in this embodiment, and it can be seen that: the primary concentric spherical lens 1, the secondary relay image rotation micro lens group 2, the three-stage concentric light splitting imaging lens group 3 and the detector 4 follow the principle of system object images of each stage: the image of the upper system is the object of the lower system.
Referring to fig. 3 to 5, the schematic diagrams are optical structure diagrams of imaging systems at different levels in the push-broom type airborne hyperspectral imaging system with an ultra-large field of view provided by this embodiment. FIG. 3 is a primary concentric spherical lens system of the imaging system, which is composed of 4 cemented spherical lenses, and sequentially comprises a negative meniscus spherical lens 11, a positive plano-convex spherical lens 12, a positive plano-convex spherical lens 13, a negative meniscus spherical lens 14, and an image plane 15 of the primary concentric spherical lens along the incident direction of light; fig. 4 shows a single secondary relay image-rotating micro lens, the system is composed of 6 spherical mirrors, a spherical positive lens 21, two groups of double-cemented lenses are a spherical positive lens 22, a spherical negative lens 23, a spherical negative lens 24, a spherical positive lens 25 and a spherical negative lens 26 respectively; the image surface 15 of the primary concentric spherical lens is subjected to field-splitting relay imaging through a secondary relay image-rotating micro lens; fig. 5 is a three-stage concentric spectroscopic imaging system, which is integrated on an optical glass substrate 31, and sequentially comprises a main mirror 32, a convex spherical linear groove holographic grating 33, and three mirrors 34 along the incident direction of light, wherein the main mirror 32 and the three mirrors 34 are spherical reflectors and are located on the back spherical surface of the glass substrate 31, and the grating 33 is located on the front concave surface of the glass substrate 31.
Referring to fig. 6, which is a schematic diagram of an optical path of the ultra-large field-of-view push-broom airborne hyperspectral imaging system provided in this embodiment, three channels ①, ② and ③ are marked in the diagram, and along the light incidence direction, a negative meniscus spherical lens 11, a positive plano-convex spherical lens 12, a positive plano-convex spherical lens 13, a negative meniscus spherical lens 14, an image plane 15 of the primary concentric spherical lens, a positive spherical lens 21, a positive spherical lens 22, a negative spherical lens 23, a negative spherical lens 24, a positive spherical lens 25 and a negative spherical lens 26 of the secondary relay image-rotating microlens are sequentially arranged, and are followed by three-stage concentric spectroscopic imaging system parts of the hyperspectral imaging system, which are composed of a main mirror 32, a grating 33 and three mirrors 34 and are simultaneously integrated on a lens glass substrate 31, the optical path design of the system is based on an Offner relay system, which satisfies telecentric object imaging, in fig. 6, the incident slit 27 is an image formed by the primary and the secondary relay image-rotating microlens system, an image passes through the slit system, finally, reaches a holographic receiver by a primary spectrometer 27, and the three-ray-incident slits are uniformly converged on a primary optical grating 13, and the primary optical grating optical system, and the three-beam receiver realizes that the three-beam-incident light beams reach a holographic optical system, and the three-incident slit achieves the holographic optical system, and the three-beam receiver, and the three-incident optical system optical.
In the push-broom type airborne hyperspectral imaging system with an oversized view field provided by the embodiment, the relevant parameters of the primary system and the secondary system corresponding to each optical element are as follows: the focal length of the primary system is 100mm, the focal length of the secondary system is 27mm, the focal length of a single-channel optical system formed by combining the primary system and the secondary system is 50mm, and the curvature radiuses of the negative meniscus spherical lens 11, the positive plano-convex spherical lens 12, the positive plano-convex spherical lens 13, the negative meniscus spherical lens 14, the front group objective lens image surface 15, the positive spherical lens 21, the positive spherical lens 22, the negative spherical lens 23, the negative spherical lens 24, the positive spherical lens 25 and the negative spherical lens 26 are 47.81mm, 26.43mm, -28mm, -47.92mm, -100mm, 65.12mm, -16.98mm, 8.58mm, -5.26mm, -9.41mm, 9.22mm, 11.75mm, -11.83mm, -7.05mm and 43.34mm in sequence along the light incidence direction.
The specific parameters of the three-stage concentric spectral imaging system are as follows: the focal length is 120mm, the curvature radius of the main mirror 32 is-27 mm, the curvature radius of the grating 33 is-13.5 mm, and the curvature radius of the three mirrors 34 is the same; the curvature radius when normalized relative to the focal length of the lens is respectively
，
，
(ii) a The four intervals are respectively as follows in sequence: the distance between the slit 27 and the main mirror 32 is 26mm, the distance between the main mirror 32 and the grating 33 is-13 mm, the distance between the grating 33 and the three mirrors 34 is 13mm, and the distance between the three mirrors 34 and the image plane 35 is-26 mm. The grating constant was 400lp/mm and the refractive index of the material of the glass substrate 31 was 1.49.
By adopting the push-broom type airborne hyperspectral imaging system with the ultra-large view field provided by the embodiment, the imaging method comprises the following steps: a large-field-of-view target object passes through a primary concentric spherical lens system to obtain a middle curved image with uniform aberration; the middle curved surface image of the large view field is used as a target object of a secondary relay image transfer micro lens, and a plurality of groups of small view field images are obtained after the secondary relay image transfer micro lens group forms a view field relay image; and after the group of small visual field images are subjected to relay imaging by the light splitting system, spectral images with different wavelengths of the sub-visual field are obtained on a detector, and then the adjacent group of small visual field spectral images are spliced and fused to obtain a spectral image with an ultra-large visual field range.
Referring to fig. 7, which is a light ray tracing point diagram of a light ray passing through the optical system described in this embodiment, circles with different wavelengths at different fields in fig. 7 represent Airy spots, and it can be seen from the diagram that 95% of the point diagrams at different fields with different wavelengths on the image plane fall within the Airy spots, indicating that the optical system has a focusing characteristic close to the theoretical limit of diffraction.
Referring to fig. 8, which is an energy concentration curve of the optical system according to the present embodiment, it can be seen from fig. 8 that more than 85% of the energy is concentrated in the Airy spot range.
Referring to fig. 9, which is a graph of relative irradiance distribution of the optical system of the present embodiment on the receiver surface, since the system satisfies image-side telecentricity, it can be seen from the graph that the image-side illuminance distribution is very uniform, and the edge illuminance is only slightly decreased.
Referring to fig. 10, which is a modulation transfer function curve of the optical system according to the present embodiment, it can be seen that the optical system has an imaging performance close to the diffraction limit.
Claims (7)
1. The utility model provides a super large field of view pushes away formula of sweeping machine carries high spectral imaging system which characterized in that: the system is a cascade optical imaging structure and sequentially comprises a primary concentric spherical lens system, a secondary relay image-rotating micro lens group, a three-stage concentric light splitting imaging lens group and a detector focal plane along the light incidence direction, wherein the primary concentric spherical lens system and the three-stage concentric light splitting imaging lens group are respectively positioned on two sides of an aperture diaphragm, and the hyperspectral imaging system meets the requirement of image space telecentric imaging;
the primary concentric spherical lens system is of a concentric asymmetric structure and has a focal lengthf 1 Is less than or equal to 80mmf 1 Less than or equal to 110 mm; the optical elements are a first negative meniscus spherical lens (11), a first positive plano-convex spherical lens (12), a second positive plano-convex spherical lens (13) and a second negative meniscus spherical lens (14) in sequence, and the normalized value of the focal length of each lens relative to the focal length of the system corresponds tof’ 11、f’ 12、f’ 13、f’ 14Satisfies the condition of-2.88 ≤f’ 11≤-2.52、1.02≤f’ 12≤1.13、1.02≤f’ 13≤1.13、-2.88≤f’ 14Less than or equal to-2.52; the refractive index of each lens material is sequentially corresponding ton 11、n 12、n 13、n 14Satisfies the condition of 1.65 ≤n 11≤1.90、1.45≤n 12≤2.0、1.45≤n 13≤2.0、1.65≤n 14≤1.90；
The secondary relay image transfer micro lens group comprises a plurality of sub imaging systems and the focal length of a single sub imaging systemf 2 Is less than or equal to 25mmf 2 Less than or equal to 30 mm; the optical elements are a first biconvex lens (21), a first biconvex lens group (22), a second biconvex lens group (23) and a first meniscus thick lens (24) in sequence, the first biconvex lens group (22) consists of a second biconvex lens (221) and a second meniscus thick lens (222), and the second biconvex lens group (23) consists of a meniscus negative lens (231) and a third biconvex lens (232); the normalized value of each lens focal length relative to the system focal length is sequentially corresponding tof’ 21、f’ 221、f’ 222、f’ 231、f’ 232 、f’ 24， Satisfies the condition of 0.52 ≤f’ 21≤0.55、0.13≤f’ 221≤0.17、-4.92≤f’ 222≤-4.58、0.88≤f’ 231≤0.93、0.26≤f’ 232≤0.29、-0.16≤f’ 24Less than or equal to-0.14; the refractive index of each lens material is sequentially corresponding ton 21、n 221、n 222、n 231、n 232、n 24Satisfies the condition of 1.50 ≤n 21≤1.80、1.40≤n 221≤1.85、1.45≤n 222≤2.0、1.45≤n 231≤2.0、1.40≤n 232≤1.85、1.45≤n 24≤2.0；
The three-stage concentric light splitting imaging lens group comprises a plurality of sub light splitting imaging systems with concentric total reflection structures, optical elements of the three-stage concentric light splitting imaging lens group are a main mirror, a grating and three mirrors in sequence, the main mirror and the three mirrors are spherical reflectors, the grating is a spherical holographic grating, and the focal length of a single sub light splitting imaging systemf 3 Is less than or equal to 100mmf 3 Less than or equal to 130mm, the normalized radius of curvature of the focal length of the imaging system is sequentially corresponding toR 32、R 33、R 34Satisfies the condition of-0.56 ≤R 32≤-0.50、-0.29≤R 33≤-0.26、-0.56≤R 34Less than or equal to-0.50, and the density of the grating grooves is 400-450 line pairs per millimeter.
2. The ultra-large field of view push-broom airborne hyperspectral imaging system of claim 1, wherein: its total focal lengthfIs less than or equal to 40mmf≤60mm。
3. The ultra-large field of view push-broom airborne hyperspectral imaging system of claim 1, wherein: the omega of the full view field is more than or equal to 0 degree and less than or equal to 140 degrees.
4. The ultra-large field of view push-broom airborne hyperspectral imaging system of claim 1, wherein: the length L of the optical cylinder is 240 mm-250 mm.
5. The ultra-large field of view push-broom airborne hyperspectral imaging system of claim 1, wherein: its spectral resolution is 2 nm/pixel.
6. The ultra-large field of view push-broom airborne hyperspectral imaging system of claim 1, wherein: the sub-spectroscopic imaging system of the three-level spectroscopic imaging group is integrated on a meniscus optical glass substrate with the refractive index of n, and the value range of n is more than or equal to 1nLess than or equal to 2.5, the grating is positioned on the front concave surface of the glass substrate, and the main mirror and the three mirrors are positioned on the back spherical surface of the glass substrate.
7. An imaging method of a push-broom type airborne hyperspectral imaging system with an oversized view field is characterized by comprising the following steps:
(1) a large-range target object passes through a primary concentric spherical lens system to obtain a primary image with a large view field on a first curved image surface;
(2) the large-view-field primary image obtained on the curved surface is taken as a target object of the secondary relay image transfer micro-lens group, and after the secondary relay image transfer micro-lens group performs field-of-view relay imaging, a corresponding independent field-of-view plane image is obtained on the second curved surface;
(3) the obtained independent view-dividing plane image is used as a target object of a three-level concentric spectral imaging system, and spectral images with different wavelengths of each independent view-dividing field are obtained on a detector after corresponding spectral imaging component light and relay imaging;
(4) and carrying out splicing and fusion processing on the spectral images of the sub-fields to obtain the spectral image of the ultra-large field.
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